TBI大鼠神经功能及凋亡基因表达的变化

The change of nerve function and apoptotic gene expression after traumatic brain injury in rats

目的探讨TBI大鼠神经行为学及凋亡基因Bcl-2,Bcl-xl,Caspase-3,Bax在TBI大鼠中的表达意义,为了解TBI神经行为学变化提供分子依据。方法 40只SD大鼠随机分为5组(n=8):假手术组、TBI 1 h组、TBI 6 h组、TBI 24 h组、TBI 7 d组。采用自由落体致大鼠皮质运动区脑损伤模型,术后1 d、3 d、5 d、7 d行改良神经功能缺失表(NSS)评分,观察动物运动和平衡功能缺损与恢复情况;并于不同时间点开颅取脑组织,TUNEL染色法观察脑组织细胞凋亡形态学变化,RT-PCR检测出血周围脑组织Bcl-2,Bcl-xl,Caspase-3,Bax的表达。结果与假手术组比较,TBI组NSS评分明显增加(P<0.05);进而TBI组术后第1 d、3 d、5 d、7 d对比,NSS评分又呈减少趋势,各时间点间比较,差异有统计学意义(P<0.05);RTPCR检测显示在被检测的4个凋亡因子中,仅Bcl-2在脑外伤后1 h开始降低,6 h降到最低谷,与假手术组相比,差异有统计学意义(P<0.05)。然后24 h开始回升,到7 d时上升到最高峰,与6 h组相比(P<0.05)。TUNEL染色发现TBI组术后6 h凋亡百分率显示有大量细胞凋亡,而至7 d时,凋亡百分率显著减少(P<0.05)。结论脑外伤诱导皮质细胞凋亡,神经功能先下降,而后有所恢复,其可能与皮质Bcl-2先降后升有关。

Objective Discuss neuroethology and significance of the expression of apoptotic gene Bcl-2,Bcl- xl,Caspase- 3,Bax meaning in TBI rats,to provide molecular basis for understanding the neurological deficits in TBI rats.Methods 40 SD rats were randomly divided into five groups（ n = 8） ： Sham group,traumatic brain injury 1h,traumatic brain injury 6h,traumatic brain injury 24 h group,TBI 7d group. Feeney free falling method was used to establish TBI models. Neurological function were evaluated according to the modified neurological severity score（ NSS） at 1,3,5,5days. The movement and balance deficits and recovery of the animals were observed. And at different time point brain tissue were removed. TUNEL staining method was used to observe morphology. RT-PCR was used for the detection of Bcl- 2,Bcl- xl,Caspase- 3 and Bax expression in brain tissue around bleeding.Results Compared with the sham group,NSS score in TBI groups were significantly increased（ P〈0.05）. Furthermore,NSS rates in TBI groups postoperative tended to decrease as the time went on and the differences among each time points were statistically significant（ P〈0.05）. RT-PCR analysis showed that among the detected four-apoptotic factors,only Bcl-2 began to decrease at one hour after traumatic brain injury and got the lowest after 6 hours,there was a statistically significance when compared with the sham group（ P〈0.05）. TUNEL staining found a large percentage of apoptosis in TBI group after 6h,at the 7th d,the percentage of apoptosis was significantly reduced（ P〈0. 05）. Conclusions TBI- induced apoptosis in the cortex,the nerve function firstly reduces and then been restored,it may correlated with the expression of Bcl-2.